PB2602: POPULATION-BASED STUDY OF HEMOLYTIC UREMIC SYNDROME HOSPITALIZATIONS.
Authors: Khushali Jhaveri, Karnav Modi, Aditi Saha, Humaira Sarfraz, Damian Laber
Journal: HemaSphere (2023)

Topic: 32. Platelet disorders Background: Hemolytic uremic syndrome (HUS) is a rare disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, and end-organ damage, usually renal failure. HUS diagnosis can be further divided into unspecified, infection-associated, hereditary and other. There is paucity of data on its incidence and outcomes. Aims: We aim to study the incidence, characteristics and outcomes of HUS in hospitalized patients between teaching and non-teaching hospitals. Methods: We searched 2019 and 2020 National Inpatient Sample (NIS) using International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code D59.3 to identify all adult hospitalizations with primary discharge diagnosis of HUS. The sample was then stratified based on “teaching” or “non-teaching” hospital. A hospital was considered to be a “teaching” hospital if it had an American Medical Association-approved residency program. We used the Pearson’s chi-square test to analyze categorical variables and weighted Student’s t-test to analyze continuous variables. Multivariate logistic regression analysis was performed to calculate the adjusted odds ratio for various clinical outcomes. STATA was used for the analysis, and the p-value was defined as <0.05. Results: We identified 67,774,850 weighted inpatient adult hospitalizations, of which n=50,205,842 [74%] were in teaching hospitals and n=17,569,008 [26%] in non-teaching hospitals. Among these, n=1130 (0.002%) patients had a primary discharge diagnosis of HUS. Incidence was 0.0015%(n=1020) at a teaching hospital vs.0.0002%(n=110) at a non-teaching hospital. The mean age for diagnosis was 21 years vs. 47 years in teaching and non-teaching hospitals, respectively (P<0.001), with female gender being majorly affected at both hospitals (55.4% and 77.3%, P=0.043, and both cohorts having a similar Elixhauser comorbidity index (Elixhauser et al. 1998) (3.9 vs. 3.8, P=0.760). Teaching hospitals showed a lower all-cause in-hospital mortality (3.4% vs. 4.5%, P=0.788), relatively higher rates of acute kidney injury requiring dialysis (36.3% vs. 18.2%, P=0.092), and mean total cost of hospitalization ($227069 vs. $174634.9, P=0.492), but it was not statistically significant. The mean length of stay (LOS) was significantly higher (12.2 vs. 7.8 days, P=0.024) in teaching hospitals. On multivariate regression analysis, after adjusting for demographics, hospital admitting characteristics and comorbidities, no significant differences in these outcomes were observed between teaching and non-teaching hospitals. Significantly lower comorbidity index (Moore et al. 2017) for risk of 30-day all-cause readmission (2.3 vs. 6.5, P=0.013), and a lower comorbidity index for risk of 30-day all-cause mortality (-0.1 vs. 2.5, P=0.084) was observed in teaching hospitals compared to non-teaching hospitals. Summary/Conclusion: In our study, we found that there was a higher frequency of diagnosis of HUS in teaching hospitals, suggesting a potential lack of understanding of this rare disease in non-teaching hospitals. We further found that though associated with similar mortality, longer LOS and higher hospitalization costs, patients treated at teaching hospitals have a significantly lower index for readmission, indicating a better prognosis after discharge compared to non-teaching hospital.Keywords: Thrombotic microangiopathy, Thrombocytopenia, Hemolytic anemia